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Jul 20, 2013
07/13

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Saburo Kakei; Takeshi Ikeda; Kanehisa Takasaki

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The hierarchy structure associated with a (2+1)-dimensional Nonlinear Schroedinger equation is discussed as an extension of the theory of the KP hierarchy. Several methods to construct special solutions are given. The relation between the hierarchy and a representation of toroidal Lie algebras are established by using the language of free fermions. A relation to the self-dual Yang-Mills equation is also discussed.

Source: http://arxiv.org/abs/nlin/0107065v1

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Sep 18, 2013
09/13

by
Sergei Bashinsky; Edmund Bertschinger

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We suggest that the cosmic microwave background (CMB) temperature correlation function C(theta) as a function of angle provides a direct connection between experimental data and the fundamental cosmological quantities. The evolution of inhomogeneities in the prerecombination universe is studied using their Green's functions in position space. We find that a primordial adiabatic point perturbation propagates as a sharp-edged spherical acoustic wave. Density singularities at its wavefronts create...

Source: http://arxiv.org/abs/astro-ph/0012153v2

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Jul 20, 2013
07/13

by
Hans-Christian Pauli

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This work addresses more to the technical rather than to the physical problem, how to calculate analytically the form factor $F(Q)$, the associated mean-square radius $$, and the distribution function $\Phi(x,Q^2)$ for a given light-cone wave function $\Psi_{q\bar q}(x,\vec k_{\perp})$ of the pion. They turn out to be functions of only one dimensionless parameter, which is the ratio of the constituent quark mass and an effective Bohr momentum which measures the width of the wave function in...

Source: http://arxiv.org/abs/hep-ph/0107302v1

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Jul 20, 2013
07/13

by
P. Allegrini; P. Grigolini; P. Hamilton; L. Palatella; G. Raffaelli

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We study the long-range correlations of heartbeat fluctuations with the method of diffusion entropy. We show that this method of analysis yields a scaling parameter $\delta$ that apparently conflicts with the direct evaluation of the distribution of times of sojourn in states with a given heartbeat frequency. The strength of the memory responsible for this discrepancy is given by a parameter $\epsilon^{2}$, which is derived from real data. The distribution of patients in the ($\delta$,...

Source: http://arxiv.org/abs/cond-mat/0107597v1

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Jul 20, 2013
07/13

by
Marco Airoldi

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Fat tails in financial time series and increase of stocks cross-correlations in high volatility periods are puzzling facts that ask for new paradigms. Both points are of key importance in fundamental research as well as in Risk Management (where extreme losses play a key role). In this paper we present a new model for an ensemble of stocks that aims to encompass in a unitary picture both these features. Equities are modelled as quasi random walk variables, where the non-Brownian components of...

Source: http://arxiv.org/abs/cond-mat/0107593v1

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Jul 20, 2013
07/13

by
Valeria Del Prete; Alessandro Treves

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In a previous report we have evaluated analytically the mutual information between the firing rates of N independent units and a set of multi-dimensional continuous+discrete stimuli, for a finite population size and in the limit of large noise. Here, we extend the analysis to the case of two interconnected populations, where input units activate output ones via gaussian weights and a threshold linear transfer function. We evaluate the information carried by a population of M output units, again...

Source: http://arxiv.org/abs/cond-mat/0107587v1

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Sep 18, 2013
09/13

by
A. Bashir; R. Delbourgo; M. L. Roberts

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We derive expressions for the phase-space of a particle of momentum $p$ decaying into $N$ particles, that are valid for any number of dimensions. These are the imaginary parts of so-called `sunset' diagrams, which we also obtain. The results are given as a series of hypergeometric functions, which terminate for odd dimensions and are also well-suited for deriving the threshold behaviour.

Source: http://arxiv.org/abs/hep-th/0101148v2

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Jul 20, 2013
07/13

by
Michael Dine

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For physicists, recent developments in astrophysics and cosmology present exciting challenges. We are conducting "experiments" in energy regimes some of which will be probed by accelerators in the near future, and others which are inevitably the subject of more speculative theoretical investigations. Dark matter is an area where we have hope of making discoveries both with accelerator experiments and dedicated searches. Inflation and dark energy lie in regimes where presently our only...

Source: http://arxiv.org/abs/hep-th/0107259v1

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Jul 20, 2013
07/13

by
Steven Furlanetto; Abraham Loeb

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We propose to use gravitational wakes as a direct observational probe of the collisional nature of the dark matter. We calculate analytically the structure of a wake generated by the motion of a galaxy in the core of an X-ray cluster for dark matter in the highly-collisional and collisionless limits. We show that the difference between these limits can be recovered from detailed X-ray or weak lensing observations. We also discuss the sizes of sub-halos in these limits. Preliminary X-ray data on...

Source: http://arxiv.org/abs/astro-ph/0107567v1

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Jul 20, 2013
07/13

by
Einan Gardi; Georges Grunberg

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The large-order behaviour of QCD is dominated by renormalons. On the other hand renormalons do not occur in conformal theories, such as the one describing the infrared fixed-point of QCD at small beta_0 (the Banks--Zaks limit). Since the fixed-point has a perturbative realization, all-order perturbative relations exist between the conformal coefficients, which are renormalon-free, and the standard perturbative coefficients, which contain renormalons. Therefore, an explicit cancellation of...

Source: http://arxiv.org/abs/hep-ph/0107300v1

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Jul 20, 2013
07/13

by
M. Braden; O. Friedt; Y. Sidis; P. Bourges; M. Minakata; Y. Maeno

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In $\rm Sr_2RuO_4$ the spin excitation spectrum is dominated by incommensurate fluctuations at q=(0.3 0.3 q$_z$), which arise from Fermi-surface nesting. We show that upon Ti substitution, known to suppress superconductivity, a short range magnetic order develops with a propagation vector (0.307 0.307 1). This finding confirms that superconducting $\rm Sr_2RuO_4$ is extremely close to an incommensurate spin density wave instability. In addition, the ordered moment in \srton ~ points along the...

Source: http://arxiv.org/abs/cond-mat/0107579v2

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Jul 20, 2013
07/13

by
Sitabhra Sinha; David J. Christini

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Reentry around non-conducting ventricular scar tissue, which often causes lethal arrhythmias, is typically treated by rapid stimulation from an implantable defibrillator. However, the mechanisms of termination (success and failure) are poorly understood. To elucidate such mechanisms, we studied pacing of anatomical reentry in 1-D and 2-D excitable cardiac media models. Our results suggest that the existence of inhomogeneity in the reentry circuit is essential for pacing termination of...

Source: http://arxiv.org/abs/nlin/0107070v1

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Jul 20, 2013
07/13

by
J. N. Moore; E. P. S. Shellard; C. J. A. P. Martins

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We study the evolution of Abelian-Higgs string networks in large-scale numerical simulations in both a static and expanding background. We measure the properties of the network by tracing the motion of the string cores, for the first time estimating the rms velocity of the strings and the invariant string length, that is, the true network energy density. These results are compared with a velocity-dependent one scale model for cosmic string network evolution. This incorporates the contributions...

Source: http://arxiv.org/abs/hep-ph/0107171v3

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Jul 20, 2013
07/13

by
Leticia F. Cugliandolo

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We review an scenario for the non-equilibrium dynamics of glassy systems that has been motivated by the exact solution of simple models. This approach allows one to set on firmer grounds well-known phenomenological theories. The old ideas of entropy crisis, fictive temperatures, free-volume... have clear definitions within these models. Aging effects in the glass phase are also captured. One of the salient features of the analytic solution, the breakdown of the fluctuation-dissipation...

Source: http://arxiv.org/abs/cond-mat/0107596v1

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Sep 18, 2013
09/13

by
Winfried Bruns; Joseph Gubeladze

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We investigate similarities between the category of vector spaces and that of polytopal algebras, containing the former as a full subcategory. In Section 2 we introduce the notion of a polytopal Picard group and show that it is trivial for fields. The coincidence of this group with the ordinary Picard group for general rings remains an open question. In Section 3 we survey some of the previous results on the automorphism groups and retractions. These results support a general conjecture...

Source: http://arxiv.org/abs/math/0002024v3

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Jul 20, 2013
07/13

by
A. Nehme; P. Talavera

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We evaluate the matrix elements for the processes pi^0 K^0 -> pi^0 K^0 and pi^- K^+ -> pi^0 K^0 in the presence of isospin breaking terms at leading and next-to-leading order. As a direct application the releveant combination of the S-wave scattering lengths involved in the pion-kaon atom lifetime is determined. We discuss the sensitivity of the results with respect to the input parameters.

Source: http://arxiv.org/abs/hep-ph/0107299v1

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Jul 20, 2013
07/13

by
Laura Maraschi

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Advances in the capabilities of X-ray, gamma-ray and TeV telescopes have brought new information on the physics of relativistic jets, which are responsible for the blazar "phenomenon". In particular the broad band sensitivity of the BeppoSAX satellite, extending up to 100 KeV has allowed unprecedented studies of their hard X-ray spectra. I summarize here some basic results and present a unified view of the blazar population, whereby all sources contain essentially similar jets despite...

Source: http://arxiv.org/abs/astro-ph/0107565v1

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Sep 22, 2013
09/13

by
Daniel Collins; Sandu Popescu

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Results obtained in two recent papers, \cite{Kaszlikowski} and \cite{Durt}, seem to indicate that the nonlocal character of the correlations between the outcomes of measurements performed on entangled systems separated in space is not robust in the presence of noise. This is surprising, since entanglement itself is robust. Here we revisit this problem and argue that the class of gedanken-experiments considered in \cite{Kaszlikowski} and \cite{Durt} is too restrictive. By considering a more...

Source: http://arxiv.org/abs/quant-ph/0106156v2

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Sep 17, 2013
09/13

by
Vladimir Kondratiev; Mikhail Shubin

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We provide sufficient conditions for the discreteness of spectrum for magnetic Schr\"odinger operators. They generalize the classical result by K.Friedrichs (1934) and earlier results by J.Avron, I.Herbst and B.Simon (1978), A.Dufresnoy (1983) and A.Iwatsuka (1990) which were obtained in the absence of electric field. Our conditions are formulated as conditions of growth at infinity for some effective potentials. More precise sufficient conditions are formulated by use of the Wiener...

Source: http://arxiv.org/abs/math/0007111v2

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Jul 20, 2013
07/13

by
Anne Schilling

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q-Supernomial coefficients are generalizations of the q-binomial coefficients. They can be defined as the coefficients of the Hall-Littlewood symmetric function in a product of the complete symmetric functions or the elementary symmetric functions. Hatayama et al. give explicit expressions for these q-supernomial coefficients. A combinatorial expression as the generating function of ribbon tableaux with (co)spin statistic follows from the work of Lascoux, Leclerc and Thibon. In this paper we...

Source: http://arxiv.org/abs/math/0107214v1

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Jul 20, 2013
07/13

by
A. Marchewka; Zeev Schuss

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We consider the evolution of Green's function of the one-dimensional Schr\"odinger equation in the presence of the complex potential $-ik\delta(x)$. Our result is the construction of an explicit time-dependent solution which we use to calculate the time-dependent survival probability of a quantum particle. The survival probability decays to zero in finite time, which means that the complex delta potential well is a total absorber for quantum particles. This potential can be interpreted as...

Source: http://arxiv.org/abs/quant-ph/0107152v1

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Jul 20, 2013
07/13

by
M. Czakon; J. Gluza; M. Zralek

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A formal proof is given that in a see-saw type neutrino mass matrix with only two neutrino mass scales ($m_D \ll m_R$) and the maximal rank of $m_{R(D)}$, we can not get a fourth light sterile neutrino.

Source: http://arxiv.org/abs/hep-ph/0107298v1

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Jul 20, 2013
07/13

by
Konstantin Klemm; Victor M. Eguiluz

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In the context of growing networks, we introduce a simple dynamical model that unifies the generic features of real networks: scale-free distribution of degree and the small world effect. While the average shortest path length increases logartihmically as in random networks, the clustering coefficient assumes a large value independent of system size. We derive expressions for the clustering coefficient in two limiting cases: random (C ~ (ln N)^2 / N) and highly clustered (C = 5/6) scale-free...

Source: http://arxiv.org/abs/cond-mat/0107607v1

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Jul 20, 2013
07/13

by
S. Recchi; F. Matteucci; A. D'Ercole

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In this paper we present some results of numerical simulations concerning the development of galactic winds in starburst galaxies. In particular, we focus on a galaxy similar to IZw18, the most metal-poor galaxy locally known. We compute the chemio-dynamical evolution of this galaxy, considering the energetic input and the chemical yields originating from Supernovae (SNe) of Type II and Ia and from intermediate-mass stars. We consider both single, instantaneous starburst and two starbursts...

Source: http://arxiv.org/abs/astro-ph/0107561v1

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Sep 24, 2013
09/13

by
V. G. Arkhipkin; I. V. Timofeev

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Spatial and temporal evolution is studied of two powerful short laser pulses having different wavelengths and interacting with a dense three-level Lambda-type optical medium under coherent population trapping. A general case of unequal oscillator strengths of the transitions is considered. Durations of the probe pulse and the coupling pulse $T_{1,2}$ ($T_2>T_1$) are assumed to be shorter than any of the relevant atomic relaxation times. We propose analytical and numerical solutions of a...

Source: http://arxiv.org/abs/quant-ph/0103130v2

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Jul 20, 2013
07/13

by
A. Albrecht; C. P. Burgess; F. Ravndal; C. Skordis

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We examine the late-time (nucleosynthesis and later) cosmological implications of brane-world scenarios having large (millimeter sized) extra dimensions. In particular, recent proposals for understanding why the extra dimensions are so large in these models indicate that moduli like the radion appear (to four-dimensional observers) to be extremely light, with a mass of order 10^{-33} eV, allowing them to play the role of the light scalar of quintessence models. The radion-as-quintessence solves...

Source: http://arxiv.org/abs/astro-ph/0107573v1

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Jul 20, 2013
07/13

by
Michael J. W. Hall

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The Heisenberg inequality \Delta X \Delta P \geq \hbar/2 can be replaced by an exact equality, for suitably chosen measures of position and momentum uncertainty, which is valid for all wavefunctions. The statistics of complementary observables are thus connected by an ``exact'' uncertainty relation.

Source: http://arxiv.org/abs/quant-ph/0107149v1

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Sep 18, 2013
09/13

by
Rong-Gen Cai; Yun Soo Myung; Nobuyoshi Ohta

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We obtain a Bekenstein entropy bound for the charged objects in arbitrary dimensions ($D\ge 4$) using the D-bound recently proposed by Bousso. With the help of thermodynamics of CFTs corresponding to AdS Reissner-Norstr\"om (RN) black holes, we discuss the relation between the Bekenstein and Bekenstein-Verlinde bounds. In particular we propose a Bekenstein-Verlinde-like bound for the charged systems. In the Einstein-Maxwell theory with a negative cosmological constant, we discuss the brane...

Source: http://arxiv.org/abs/hep-th/0105070v2

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Jul 20, 2013
07/13

by
F. Ngakeu; S. Majid; D. Lambert

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We study the noncommutative Riemannian geometry of the alternating group $A_4=(Z_2 \times Z_2)\cross Z_3$ using a recent formulation for finite groups. We find a unique `Levi-Civita' connection for the invariant metric, and find that it has Ricci-flat but nonzero Riemann curvature. We show that it is the unique Ricci-flat connection on $A_4$ with the standard framing (we solve the vacuum Einstein's equation). We also propose a natural Dirac operator for the associated spin connection and solve...

Source: http://arxiv.org/abs/math/0107216v1

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Jul 20, 2013
07/13

by
Alberto Accardi

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At ultra-relativistic energies the minijet production in heavy-ion collisions becomes sensitive to semi-hard parton rescatterings in the initial stages of the process. As a result global characteristics of the event, like the initial minijet density, become rather insensitive on the infrared cutoff that separates hard and soft interactions. This allows to define a nearly parameter-free {\it saturation cutoff} at which the initial conditions may be computed. As an application we study the...

Source: http://arxiv.org/abs/hep-ph/0107301v1

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Jul 20, 2013
07/13

by
Carl E. Carlson; Christopher D. Carone; Richard F. Lebed

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Jurco, Moller, Schraml, Schupp, and Wess have shown how to construct noncommutative SU(N) gauge theories from a consistency relation. Within this framework, we present the Feynman rules for noncommutative QCD and compute explicitly the most dangerous Lorentz-violating operator generated through radiative corrections. We find that interesting effects appear at the one-loop level, in contrast to conventional noncommutative U(N) gauge theories, leading to a stringent bound. Our results are...

Source: http://arxiv.org/abs/hep-ph/0107291v2

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Jul 20, 2013
07/13

by
Jelte de Jong; Penny D. Sackett; Konrad Kuijken; Robert Uglesich; Arlin Crotts; Will Sutherland

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One of the possible astrophysical solutions to the galactic dark matter problem is the presence of a significant amount of ``dark'' compact objects (MACHOs) in galactic dark matter halos. MEGA (Microlensing Exploration of the Galaxy and Andromeda) tries to find proof for or against the presence of compact objects in the halo of the Andromeda galaxy (M31) by looking for the microlensing signature that would be induced by these objects. The lightcurves presented here are preliminary and based on...

Source: http://arxiv.org/abs/astro-ph/0107560v1

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Sep 18, 2013
09/13

by
Robert Alicki; Michal Horodecki; Pawel Horodecki; Ryszard Horodecki

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We develop dynamical non-Markovian description of quantum computing in weak coupling limit, in lowest order approximation. We show that long range memory of quantum reservoir produces strong interrelation between structure of noise and quantum algorithm, implying nonlocal attacks of noise. We then argue that the quantum error correction method fails to protect quantum computation against electromagnetic or phonon vacuum which exhibit $1/t^4$ memory. This shows that the implicit assumption of...

Source: http://arxiv.org/abs/quant-ph/0105115v2

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Jul 20, 2013
07/13

by
Sanjay K. Ghosh; Byron K. Jennings

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The nuclear density of states plays an important role in nuclear reactions. At high energies, above a few MeV, the nuclear density of states is well described by a formula that depends on the smooth single particle density of states at the Fermi surface, the nuclear shell correction and the pairing energy. In this paper we present an analysis of the low energy behaviour of the nuclear density of states using the saddle point approximation and extensions to it. Furthermore, we prescribe a simple...

Source: http://arxiv.org/abs/nucl-th/0107074v1

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Sep 18, 2013
09/13

by
Annalisa Bossi; Nicoletta Cocco; Sandro Etalle; Sabina Rossi

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We propose a modular method for proving termination of general logic programs (i.e., logic programs with negation). It is based on the notion of acceptable programs, but it allows us to prove termination in a truly modular way. We consider programs consisting of a hierarchy of modules and supply a general result for proving termination by dealing with each module separately. For programs which are in a certain sense well-behaved, namely well-moded or well-typed programs, we derive both a simple...

Source: http://arxiv.org/abs/cs/0005018v2

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Sep 18, 2013
09/13

by
Charles H. Bennett; David P. DiVincenzo; Peter W. Shor; John A. Smolin; Barbara M. Terhal; William K. Wootters

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Quantum teleportation uses prior entanglement and forward classical communication to transmit one instance of an unknown quantum state. Remote state preparation (RSP) has the same goal, but the sender knows classically what state is to be transmitted. We show that the asymptotic classical communication cost of RSP is one bit per qubit - half that of teleportation - and becomes even less when transmitting part of a known entangled state. We explore the tradeoff between entanglement and classical...

Source: http://arxiv.org/abs/quant-ph/0006044v5

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Sep 22, 2013
09/13

by
Georges Grunberg

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The normalization of the gluon condensate and of renormalon-related power corrections in QCD is computed under the assumption that their ``perturbative'' part dominates over any eventual extra contribution from the non-trivial vacuum. The calculation is performed in the infrared finite coupling framework, assuming an infrared fixed point is present in the perturbative coupling down to low values of N_f. The freezing perturbative coupling is reconstructed using a Banks-Zaks expansion approach....

Source: http://arxiv.org/abs/hep-ph/0106070v2

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Jul 20, 2013
07/13

by
Curtis J. Saxton; Ralph S. Sutherland; Geoffrey V. Bicknell

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We model the northern middle radio lobe of Centaurus A (NGC 5128) as a buoyant bubble of plasma deposited by an intermittently active jet. The extent of the rise of the bubble and its morphology imply that the ratio of its density to that of the surrounding ISM is less than 10^{-2}, consistent with our knowledge of extragalactic jets and minimal entrainment into the precursor radio lobe. Using the morphology of the lobe to date the beginning of its rise through the atmosphere of Centaurus A, we...

Source: http://arxiv.org/abs/astro-ph/0107558v1

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Jul 20, 2013
07/13

by
D. J. Dean; T. Papenbrock

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We study precursors of thermal phase transitions in finite systems of interacting Bose gases. For weakly repulsive interactions there is a phase transition to the one-vortex state. The distribution of zeros of the partition function indicates that this transition is first order, and the precursors of the phase transition are already displayed in systems of a few dozen bosons. Systems of this size do not exhibit new phases as more vortices are added to the system.

Source: http://arxiv.org/abs/cond-mat/0107613v1

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Jul 20, 2013
07/13

by
Yshai Avishai; Yigal Meir

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Using heuristic arguments and numerical simulations it is argued that the critical exponent $\nu$ describing the localization length divergence at the quantum Hall transition is modified in the presence of spin-orbit scattering with short range correlations. The exponent is very close to $\nu=4/3$, the percolation correlation length exponent, the prediction of a semi-classical argument. In addition, a region of weakly localized regime, where the localization length is exponentially large, is...

Source: http://arxiv.org/abs/cond-mat/0107591v1

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Sep 22, 2013
09/13

by
Andrzej Sandacz; Oleg A. Grajek; Murray Moinester; Eli Piasetzky

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We examine the potential of the COMPASS experiment at CERN to study color transparency via exclusive vector meson production in hard muon-nucleus scattering. It is demonstrated that COMPASS has high sensitivity to test this important prediction of perturbative QCD.

Source: http://arxiv.org/abs/hep-ex/0106076v2

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Sep 19, 2013
09/13

by
Aurel Bulgac; Andreas Wirzba

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Using ensembles of two, three and four spheres immersed in a fermionic background we evaluate the (integrated) density of states and the Casimir energy. We thus infer that for sufficiently smooth objects, whose various geometric characteristic lengths are larger then the Fermi wave length one can use the simplest semiclassical approximation (the contribution due shortest periodic orbits only) to evaluate the Casimir energy. We also show that the Casimir energy for several objects can be...

Source: http://arxiv.org/abs/nucl-th/0102018v2

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Sep 22, 2013
09/13

by
Kevin A. Pimbblet; Ian Smail; Alastair C. Edge; Warrick J. Couch; Eileen O'Hely; Ann I. Zabludoff

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The Las Campanas Observatory and Anglo--Australian Telescope Rich Cluster Survey (LARCS) is a panoramic imaging and spectroscopic survey of an X-ray luminosity-selected sample of 21 clusters of galaxies at 0.07

Source: http://arxiv.org/abs/astro-ph/0106258v2

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Jul 20, 2013
07/13

by
Yasuhiro Daikoku

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The recent measurement of the muon anomalous magnetic dipole moment shows 2.6$\sigma$ deviation of $a_\mu$ from the standard model prediction which can be explained by a chargino-sneutrino loop correction in the supersymmetric models. In this paper we consider extra U(1) models where the $\mu$ parameter is radiatively generated. This model predicts the sign of $\mu$ is positive in wide parameter regions. But even the 2$\sigma$ constraint causes a serious contradiction to the experimental bound...

Source: http://arxiv.org/abs/hep-ph/0107305v1

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Jul 20, 2013
07/13

by
D. A. Dikin; S. Jung; V. Chandrasekhar

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Using a new second derivative technique and thermometers which enable us to determine the local electron temperature in a mesoscopic metallic sample, we have obtained quantitative measurements of the low temperature field and temperature dependent thermopower of Andreev interferometers. As in previous experiments, the thermopower is found to oscillate as a function of magnetic field. The temperature dependence of the thermopower is nonmonotonic, with a minimum at a temperature of $\simeq0.5$ K....

Source: http://arxiv.org/abs/cond-mat/0107605v1

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Sep 19, 2013
09/13

by
Mladen Prester

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In cuprate superconductors superconductivity develops as a unique cross over between the two extremal phases characterizing these compounds. The extremal phases are known to be an antiferromagnetic (AF) Mott insulator one, on one side, and a non-superconducting itinerant metal on the other. Numerous inelastic neutron scattering studies on underdoped samples shows most directly that the static AF order of the parent phase does not disappear by doping but transforms in such a way that at least...

Source: http://arxiv.org/abs/cond-mat/9911458v3

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28

Jul 20, 2013
07/13

by
Keiichirou Kikuchi; Hiroshi Imamura; Saburo Takahashi; Sadamichi Maekawa

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The Andreev reflection of narrow ferromagnet/superconductor point contacts is theoretically studied. We show that the conductance quantization depends on whether the contact region is superconducting or ferromagnetic as well as on the strength of the exchange field in the ferromagnet. The Andreev reflection of the ferromagnetic contact is more suppressed than that of the superconducting contact. We also show that the conductance-voltage curve has a bump at zero bias-voltage if there is no...

Source: http://arxiv.org/abs/cond-mat/0107588v1

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41

Jul 20, 2013
07/13

by
Konstantin Klemm; Victor M. Eguiluz

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We propose a model for growing networks based on a finite memory of the nodes. The model shows stylized features of real-world networks: power law distribution of degree, linear preferential attachment of new links and a negative correlation between the age of a node and its link attachment rate. Notably, the degree distribution is conserved even though only the most recently grown part of the network is considered. This feature is relevant because real-world networks truncated in the same way...

Source: http://arxiv.org/abs/cond-mat/0107606v1

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65

Jul 20, 2013
07/13

by
N. S. Averkiev; L. E. Golub

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Spin relaxation in-plane anisotropy is predicted for heterostructures based on zinc-blende semiconductors. It is shown that it manifests itself especially brightly if the two spin relaxation mechanisms (D'yakonov-Perel' and Rashba) are comparable in efficiency. It is demonstrated that for the quantum well grown along the [0 0 1] direction, the main axes of spin relaxation rate tensor are [1 1 0] and [1 -1 0].

Source: http://arxiv.org/abs/cond-mat/0107599v1

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80

Jul 20, 2013
07/13

by
Andrew P. Iyengar; Ying-Jer Kao; Qijin Chen; K. Levin

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We demonstrate that the observed dependences of $T_c$ and $T^*$ on small magnetic fields can be readily understood in a precursor superconductivity approach to the pseudogap phase. In this approach, the presence of a pseudogap at $T_c$ (but not at $T^*$) and the associated suppression of the density of states lead to very different sensitivities to pair-breaking perturbations for the two temperatures. Our semi-quantitative results address the puzzling experimental observation that the coherence...

Source: http://arxiv.org/abs/cond-mat/0107614v1